/*
 * Copyright (c) 2013 Grzegorz Kostka (kostka.grzegorz@gmail.com)
 *
 *
 * HelenOS:
 * Copyright (c) 2012 Martin Sucha
 * Copyright (c) 2012 Frantisek Princ
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/** @addtogroup lwext4
 * @{
 */
/**
 * @file  ext4_fs.c
 * @brief More complex filesystem functions.
 */

#include <ext4_config.h>
#include <ext4_types.h>
#include <ext4_misc.h>
#include <ext4_errno.h>
#include <ext4_debug.h>

#include <ext4_trans.h>
#include <ext4_fs.h>
#include <ext4_blockdev.h>
#include <ext4_super.h>
#include <ext4_crc32.h>
#include <ext4_block_group.h>
#include <ext4_balloc.h>
#include <ext4_bitmap.h>
#include <ext4_inode.h>
#include <ext4_ialloc.h>
#include <ext4_extent.h>

#include <libs/klibc.h>

int ext4_fs_init(struct ext4_fs *fs, struct ext4_blockdev *bdev,
                 bool read_only) {
    int r, i;
    uint16_t tmp;
    uint32_t bsize;

    ext4_assert(fs && bdev);

    fs->bdev = bdev;

    fs->read_only = read_only;

    r = ext4_sb_read(fs->bdev, &fs->sb);
    if (r != EOK)
        return r;

    if (!ext4_sb_check(&fs->sb))
        return ENOTSUP;

    bsize = ext4_sb_get_block_size(&fs->sb);
    if (bsize > EXT4_MAX_BLOCK_SIZE)
        return ENXIO;

    r = ext4_fs_check_features(fs, &read_only);
    if (r != EOK)
        return r;

    if (read_only)
        fs->read_only = read_only;

    /* Compute limits for indirect block levels */
    uint32_t blocks_id = bsize / sizeof(uint32_t);

    fs->inode_block_limits[0] = EXT4_INODE_DIRECT_BLOCK_COUNT;
    fs->inode_blocks_per_level[0] = 1;

    for (i = 1; i < 4; i++) {
        fs->inode_blocks_per_level[i] =
            fs->inode_blocks_per_level[i - 1] * blocks_id;
        fs->inode_block_limits[i] =
            fs->inode_block_limits[i - 1] + fs->inode_blocks_per_level[i];
    }

    /*Validate FS*/
    tmp = ext4_get16(&fs->sb, state);
    if (tmp & EXT4_SUPERBLOCK_STATE_ERROR_FS)
        ext4_dbg(DEBUG_FS,
                 DBG_WARN "last umount error: superblock fs_error flag\n");

    if (!fs->read_only) {
        /* Mark system as mounted */
        ext4_set16(&fs->sb, state, EXT4_SUPERBLOCK_STATE_ERROR_FS);
        r = ext4_sb_write(fs->bdev, &fs->sb);
        if (r != EOK)
            return r;

        /*Update mount count*/
        ext4_set16(&fs->sb, mount_count, ext4_get16(&fs->sb, mount_count) + 1);
    }

    return r;
}

int ext4_fs_fini(struct ext4_fs *fs) {
    ext4_assert(fs);

    /*Set superblock state*/
    ext4_set16(&fs->sb, state, EXT4_SUPERBLOCK_STATE_VALID_FS);

    if (!fs->read_only)
        return ext4_sb_write(fs->bdev, &fs->sb);

    return EOK;
}

static void ext4_fs_debug_features_inc(uint32_t features_incompatible) {
    if (features_incompatible & EXT4_FINCOM_COMPRESSION)
        ext4_dbg(DEBUG_FS, DBG_NONE "compression\n");
    if (features_incompatible & EXT4_FINCOM_FILETYPE)
        ext4_dbg(DEBUG_FS, DBG_NONE "filetype\n");
    if (features_incompatible & EXT4_FINCOM_RECOVER)
        ext4_dbg(DEBUG_FS, DBG_NONE "recover\n");
    if (features_incompatible & EXT4_FINCOM_JOURNAL_DEV)
        ext4_dbg(DEBUG_FS, DBG_NONE "journal_dev\n");
    if (features_incompatible & EXT4_FINCOM_META_BG)
        ext4_dbg(DEBUG_FS, DBG_NONE "meta_bg\n");
    if (features_incompatible & EXT4_FINCOM_EXTENTS)
        ext4_dbg(DEBUG_FS, DBG_NONE "extents\n");
    if (features_incompatible & EXT4_FINCOM_64BIT)
        ext4_dbg(DEBUG_FS, DBG_NONE "64bit\n");
    if (features_incompatible & EXT4_FINCOM_MMP)
        ext4_dbg(DEBUG_FS, DBG_NONE "mnp\n");
    if (features_incompatible & EXT4_FINCOM_FLEX_BG)
        ext4_dbg(DEBUG_FS, DBG_NONE "flex_bg\n");
    if (features_incompatible & EXT4_FINCOM_EA_INODE)
        ext4_dbg(DEBUG_FS, DBG_NONE "ea_inode\n");
    if (features_incompatible & EXT4_FINCOM_DIRDATA)
        ext4_dbg(DEBUG_FS, DBG_NONE "dirdata\n");
    if (features_incompatible & EXT4_FINCOM_BG_USE_META_CSUM)
        ext4_dbg(DEBUG_FS, DBG_NONE "meta_csum\n");
    if (features_incompatible & EXT4_FINCOM_LARGEDIR)
        ext4_dbg(DEBUG_FS, DBG_NONE "largedir\n");
    if (features_incompatible & EXT4_FINCOM_INLINE_DATA)
        ext4_dbg(DEBUG_FS, DBG_NONE "inline_data\n");
}
static void ext4_fs_debug_features_comp(uint32_t features_compatible) {
    if (features_compatible & EXT4_FCOM_DIR_PREALLOC)
        ext4_dbg(DEBUG_FS, DBG_NONE "dir_prealloc\n");
    if (features_compatible & EXT4_FCOM_IMAGIC_INODES)
        ext4_dbg(DEBUG_FS, DBG_NONE "imagic_inodes\n");
    if (features_compatible & EXT4_FCOM_HAS_JOURNAL)
        ext4_dbg(DEBUG_FS, DBG_NONE "has_journal\n");
    if (features_compatible & EXT4_FCOM_EXT_ATTR)
        ext4_dbg(DEBUG_FS, DBG_NONE "ext_attr\n");
    if (features_compatible & EXT4_FCOM_RESIZE_INODE)
        ext4_dbg(DEBUG_FS, DBG_NONE "resize_inode\n");
    if (features_compatible & EXT4_FCOM_DIR_INDEX)
        ext4_dbg(DEBUG_FS, DBG_NONE "dir_index\n");
}

static void ext4_fs_debug_features_ro(uint32_t features_ro) {
    if (features_ro & EXT4_FRO_COM_SPARSE_SUPER)
        ext4_dbg(DEBUG_FS, DBG_NONE "sparse_super\n");
    if (features_ro & EXT4_FRO_COM_LARGE_FILE)
        ext4_dbg(DEBUG_FS, DBG_NONE "large_file\n");
    if (features_ro & EXT4_FRO_COM_BTREE_DIR)
        ext4_dbg(DEBUG_FS, DBG_NONE "btree_dir\n");
    if (features_ro & EXT4_FRO_COM_HUGE_FILE)
        ext4_dbg(DEBUG_FS, DBG_NONE "huge_file\n");
    if (features_ro & EXT4_FRO_COM_GDT_CSUM)
        ext4_dbg(DEBUG_FS, DBG_NONE "gtd_csum\n");
    if (features_ro & EXT4_FRO_COM_DIR_NLINK)
        ext4_dbg(DEBUG_FS, DBG_NONE "dir_nlink\n");
    if (features_ro & EXT4_FRO_COM_EXTRA_ISIZE)
        ext4_dbg(DEBUG_FS, DBG_NONE "extra_isize\n");
    if (features_ro & EXT4_FRO_COM_QUOTA)
        ext4_dbg(DEBUG_FS, DBG_NONE "quota\n");
    if (features_ro & EXT4_FRO_COM_BIGALLOC)
        ext4_dbg(DEBUG_FS, DBG_NONE "bigalloc\n");
    if (features_ro & EXT4_FRO_COM_METADATA_CSUM)
        ext4_dbg(DEBUG_FS, DBG_NONE "metadata_csum\n");
}

int ext4_fs_check_features(struct ext4_fs *fs, bool *read_only) {
    ext4_assert(fs && read_only);
    uint32_t v;
    if (ext4_get32(&fs->sb, rev_level) == 0) {
        *read_only = false;
        return EOK;
    }

    ext4_dbg(DEBUG_FS, DBG_INFO "sblock features_incompatible:\n");
    ext4_fs_debug_features_inc(ext4_get32(&fs->sb, features_incompatible));

    ext4_dbg(DEBUG_FS, DBG_INFO "sblock features_compatible:\n");
    ext4_fs_debug_features_comp(ext4_get32(&fs->sb, features_compatible));

    ext4_dbg(DEBUG_FS, DBG_INFO "sblock features_read_only:\n");
    ext4_fs_debug_features_ro(ext4_get32(&fs->sb, features_read_only));

    /*Check features_incompatible*/
    v = (ext4_get32(&fs->sb, features_incompatible) &
         (~CONFIG_SUPPORTED_FINCOM));
    if (v) {
        ext4_dbg(DEBUG_FS,
                 DBG_ERROR "sblock has unsupported features incompatible:\n");
        ext4_fs_debug_features_inc(v);
        return ENOTSUP;
    }

    /*Check features_read_only*/
    v = ext4_get32(&fs->sb, features_read_only);
    v &= ~CONFIG_SUPPORTED_FRO_COM;
    if (v) {
        ext4_dbg(DEBUG_FS,
                 DBG_WARN "sblock has unsupported features read only:\n");
        ext4_fs_debug_features_ro(v);
        *read_only = true;
        return EOK;
    }
    *read_only = false;

    return EOK;
}

/**@brief Determine whether the block is inside the group.
 * @param baddr   block address
 * @param bgid    block group id
 * @return Error code
 */
static bool ext4_block_in_group(struct ext4_sblock *s, ext4_fsblk_t baddr,
                                uint32_t bgid) {
    uint32_t actual_bgid;
    actual_bgid = ext4_balloc_get_bgid_of_block(s, baddr);
    if (actual_bgid == bgid)
        return true;
    return false;
}

/**@brief   To avoid calling the atomic setbit hundreds or thousands of times,
 * we only need to use it within a single byte (to ensure we get endianness
 * right). We can use memset for the rest of the bitmap as there are no other
 * users.
 */
static void ext4_fs_mark_bitmap_end(int start_bit, int end_bit, void *bitmap) {
    int i;

    if (start_bit >= end_bit)
        return;

    for (i = start_bit; (unsigned)i < ((start_bit + 7) & ~7UL); i++)
        ext4_bmap_bit_set(bitmap, i);

    if (i < end_bit)
        memset((char *)bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
}

/**@brief Initialize block bitmap in block group.
 * @param bg_ref Reference to block group
 * @return Error code
 */
static int ext4_fs_init_block_bitmap(struct ext4_block_group_ref *bg_ref) {
    struct ext4_sblock *sb = &bg_ref->fs->sb;
    struct ext4_bgroup *bg = bg_ref->block_group;
    int rc;

    uint32_t bit, bit_max;
    uint32_t group_blocks;
    uint16_t inode_size = ext4_get16(sb, inode_size);
    uint32_t block_size = ext4_sb_get_block_size(sb);
    uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);

    ext4_fsblk_t i;
    ext4_fsblk_t bmp_blk = ext4_bg_get_block_bitmap(bg, sb);
    ext4_fsblk_t bmp_inode = ext4_bg_get_inode_bitmap(bg, sb);
    ext4_fsblk_t inode_table = ext4_bg_get_inode_table_first_block(bg, sb);
    ext4_fsblk_t first_bg = ext4_balloc_get_block_of_bgid(sb, bg_ref->index);

    uint32_t dsc_per_block = block_size / ext4_sb_get_desc_size(sb);

    bool flex_bg = ext4_sb_feature_incom(sb, EXT4_FINCOM_FLEX_BG);
    bool meta_bg = ext4_sb_feature_incom(sb, EXT4_FINCOM_META_BG);

    uint32_t inode_table_bcnt = inodes_per_group * inode_size / block_size;

    struct ext4_block block_bitmap;
    rc = ext4_trans_block_get_noread(bg_ref->fs->bdev, &block_bitmap, bmp_blk);
    if (rc != EOK)
        return rc;

    memset(block_bitmap.data, 0, block_size);
    bit_max = ext4_sb_is_super_in_bg(sb, bg_ref->index);

    uint32_t count = ext4_sb_first_meta_bg(sb) * dsc_per_block;
    if (!meta_bg || bg_ref->index < count) {
        if (bit_max) {
            bit_max += ext4_bg_num_gdb(sb, bg_ref->index);
            bit_max += ext4_get16(sb, s_reserved_gdt_blocks);
        }
    } else { /* For META_BG_BLOCK_GROUPS */
        bit_max += ext4_bg_num_gdb(sb, bg_ref->index);
    }
    for (bit = 0; bit < bit_max; bit++)
        ext4_bmap_bit_set(block_bitmap.data, bit);

    if (bg_ref->index == ext4_block_group_cnt(sb) - 1) {
        /*
         * Even though mke2fs always initialize first and last group
         * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
         * to make sure we calculate the right free blocks
         */

        group_blocks = (uint32_t)(ext4_sb_get_blocks_cnt(sb) -
                                  ext4_get32(sb, first_data_block) -
                                  ext4_get32(sb, blocks_per_group) *
                                      (ext4_block_group_cnt(sb) - 1));
    } else {
        group_blocks = ext4_get32(sb, blocks_per_group);
    }

    bool in_bg;
    in_bg = ext4_block_in_group(sb, bmp_blk, bg_ref->index);
    if (!flex_bg || in_bg)
        ext4_bmap_bit_set(block_bitmap.data, (uint32_t)(bmp_blk - first_bg));

    in_bg = ext4_block_in_group(sb, bmp_inode, bg_ref->index);
    if (!flex_bg || in_bg)
        ext4_bmap_bit_set(block_bitmap.data, (uint32_t)(bmp_inode - first_bg));

    for (i = inode_table; i < inode_table + inode_table_bcnt; i++) {
        in_bg = ext4_block_in_group(sb, i, bg_ref->index);
        if (!flex_bg || in_bg)
            ext4_bmap_bit_set(block_bitmap.data, (uint32_t)(i - first_bg));
    }
    /*
     * Also if the number of blocks within the group is
     * less than the blocksize * 8 ( which is the size
     * of bitmap ), set rest of the block bitmap to 1
     */
    ext4_fs_mark_bitmap_end(group_blocks, block_size * 8, block_bitmap.data);
    ext4_trans_set_block_dirty(block_bitmap.buf);

    ext4_balloc_set_bitmap_csum(sb, bg_ref->block_group, block_bitmap.data);
    bg_ref->dirty = true;

    /* Save bitmap */
    return ext4_block_set(bg_ref->fs->bdev, &block_bitmap);
}

/**@brief Initialize i-node bitmap in block group.
 * @param bg_ref Reference to block group
 * @return Error code
 */
static int ext4_fs_init_inode_bitmap(struct ext4_block_group_ref *bg_ref) {
    int rc;
    struct ext4_sblock *sb = &bg_ref->fs->sb;
    struct ext4_bgroup *bg = bg_ref->block_group;

    /* Load bitmap */
    ext4_fsblk_t bitmap_block_addr = ext4_bg_get_inode_bitmap(bg, sb);

    struct ext4_block b;
    rc = ext4_trans_block_get_noread(bg_ref->fs->bdev, &b, bitmap_block_addr);
    if (rc != EOK)
        return rc;

    /* Initialize all bitmap bits to zero */
    uint32_t block_size = ext4_sb_get_block_size(sb);
    uint32_t inodes_per_group = ext4_get32(sb, inodes_per_group);

    memset(b.data, 0, (inodes_per_group + 7) / 8);

    uint32_t start_bit = inodes_per_group;
    uint32_t end_bit = block_size * 8;

    uint32_t i;
    for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
        ext4_bmap_bit_set(b.data, i);

    if (i < end_bit)
        memset(b.data + (i >> 3), 0xff, (end_bit - i) >> 3);

    ext4_trans_set_block_dirty(b.buf);

    ext4_ialloc_set_bitmap_csum(sb, bg, b.data);
    bg_ref->dirty = true;

    /* Save bitmap */
    return ext4_block_set(bg_ref->fs->bdev, &b);
}

/**@brief Initialize i-node table in block group.
 * @param bg_ref Reference to block group
 * @return Error code
 */
static int ext4_fs_init_inode_table(struct ext4_block_group_ref *bg_ref) {
    struct ext4_sblock *sb = &bg_ref->fs->sb;
    struct ext4_bgroup *bg = bg_ref->block_group;

    uint32_t inode_size = ext4_get16(sb, inode_size);
    uint32_t block_size = ext4_sb_get_block_size(sb);
    uint32_t inodes_per_block = block_size / inode_size;
    uint32_t inodes_in_group = ext4_inodes_in_group_cnt(sb, bg_ref->index);
    uint32_t table_blocks = inodes_in_group / inodes_per_block;
    ext4_fsblk_t fblock;

    if (inodes_in_group % inodes_per_block)
        table_blocks++;

    /* Compute initialization bounds */
    ext4_fsblk_t first_block = ext4_bg_get_inode_table_first_block(bg, sb);

    ext4_fsblk_t last_block = first_block + table_blocks - 1;

    /* Initialization of all itable blocks */
    for (fblock = first_block; fblock <= last_block; ++fblock) {
        struct ext4_block b;
        int rc = ext4_trans_block_get_noread(bg_ref->fs->bdev, &b, fblock);
        if (rc != EOK)
            return rc;

        memset(b.data, 0, block_size);
        ext4_trans_set_block_dirty(b.buf);

        rc = ext4_block_set(bg_ref->fs->bdev, &b);
        if (rc != EOK)
            return rc;
    }

    return EOK;
}

static ext4_fsblk_t ext4_fs_get_descriptor_block(struct ext4_sblock *s,
                                                 uint32_t bgid,
                                                 uint32_t dsc_per_block) {
    uint32_t first_meta_bg, dsc_id;
    int has_super = 0;
    dsc_id = bgid / dsc_per_block;
    first_meta_bg = ext4_sb_first_meta_bg(s);

    bool meta_bg = ext4_sb_feature_incom(s, EXT4_FINCOM_META_BG);

    if (!meta_bg || dsc_id < first_meta_bg)
        return ext4_get32(s, first_data_block) + dsc_id + 1;

    if (ext4_sb_is_super_in_bg(s, bgid))
        has_super = 1;

    return (has_super + ext4_fs_first_bg_block_no(s, bgid));
}

/**@brief  Compute checksum of block group descriptor.
 * @param sb   Superblock
 * @param bgid Index of block group in the filesystem
 * @param bg   Block group to compute checksum for
 * @return Checksum value
 */
static uint16_t ext4_fs_bg_checksum(struct ext4_sblock *sb, uint32_t bgid,
                                    struct ext4_bgroup *bg) {
    /* If checksum not supported, 0 will be returned */
    uint16_t crc = 0;
#if CONFIG_META_CSUM_ENABLE
    /* Compute the checksum only if the filesystem supports it */
    if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
        /* Use metadata_csum algorithm instead */
        uint32_t le32_bgid = to_le32(bgid);
        uint32_t orig_checksum, checksum;

        /* Preparation: temporarily set bg checksum to 0 */
        orig_checksum = bg->checksum;
        bg->checksum = 0;

        /* First calculate crc32 checksum against fs uuid */
        checksum = ext4_crc32c(EXT4_CRC32_INIT, sb->uuid, sizeof(sb->uuid));
        /* Then calculate crc32 checksum against bgid */
        checksum = ext4_crc32c(checksum, &le32_bgid, sizeof(bgid));
        /* Finally calculate crc32 checksum against block_group_desc */
        checksum = ext4_crc32c(checksum, bg, ext4_sb_get_desc_size(sb));
        bg->checksum = orig_checksum;

        crc = checksum & 0xFFFF;
        return crc;
    }
#endif
    if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_GDT_CSUM)) {
        uint8_t *base = (uint8_t *)bg;
        uint8_t *checksum = (uint8_t *)&bg->checksum;

        uint32_t offset = (uint32_t)(checksum - base);

        /* Convert block group index to little endian */
        uint32_t group = to_le32(bgid);

        /* Initialization */
        crc = ext4_bg_crc16(~0, sb->uuid, sizeof(sb->uuid));

        /* Include index of block group */
        crc = ext4_bg_crc16(crc, (uint8_t *)&group, sizeof(group));

        /* Compute crc from the first part (stop before checksum field)
         */
        crc = ext4_bg_crc16(crc, (uint8_t *)bg, offset);

        /* Skip checksum */
        offset += sizeof(bg->checksum);

        /* Checksum of the rest of block group descriptor */
        if ((ext4_sb_feature_incom(sb, EXT4_FINCOM_64BIT)) &&
            (offset < ext4_sb_get_desc_size(sb))) {

            const uint8_t *start = ((uint8_t *)bg) + offset;
            size_t len = ext4_sb_get_desc_size(sb) - offset;
            crc = ext4_bg_crc16(crc, start, len);
        }
    }
    return crc;
}

#if CONFIG_META_CSUM_ENABLE
static bool ext4_fs_verify_bg_csum(struct ext4_sblock *sb, uint32_t bgid,
                                   struct ext4_bgroup *bg) {
    if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
        return true;

    return ext4_fs_bg_checksum(sb, bgid, bg) == to_le16(bg->checksum);
}
#else
#define ext4_fs_verify_bg_csum(...) true
#endif

int ext4_fs_get_block_group_ref(struct ext4_fs *fs, uint32_t bgid,
                                struct ext4_block_group_ref *ref) {
    /* Compute number of descriptors, that fits in one data block */
    uint32_t block_size = ext4_sb_get_block_size(&fs->sb);
    uint32_t dsc_cnt = block_size / ext4_sb_get_desc_size(&fs->sb);

    /* Block group descriptor table starts at the next block after
     * superblock */
    uint64_t block_id = ext4_fs_get_descriptor_block(&fs->sb, bgid, dsc_cnt);

    uint32_t offset = (bgid % dsc_cnt) * ext4_sb_get_desc_size(&fs->sb);

    int rc = ext4_trans_block_get(fs->bdev, &ref->block, block_id);
    if (rc != EOK)
        return rc;

    ref->block_group = (void *)(ref->block.data + offset);
    ref->fs = fs;
    ref->index = bgid;
    ref->dirty = false;
    struct ext4_bgroup *bg = ref->block_group;

    if (!ext4_fs_verify_bg_csum(&fs->sb, bgid, bg)) {
        ext4_dbg(DEBUG_FS,
                 DBG_WARN "Block group descriptor checksum failed."
                          "Block group index: %" PRIu32 "\n",
                 bgid);
    }

    if (ext4_bg_has_flag(bg, EXT4_BLOCK_GROUP_BLOCK_UNINIT)) {
        rc = ext4_fs_init_block_bitmap(ref);
        if (rc != EOK) {
            ext4_block_set(fs->bdev, &ref->block);
            return rc;
        }
        ext4_bg_clear_flag(bg, EXT4_BLOCK_GROUP_BLOCK_UNINIT);
        ref->dirty = true;
    }

    if (ext4_bg_has_flag(bg, EXT4_BLOCK_GROUP_INODE_UNINIT)) {
        rc = ext4_fs_init_inode_bitmap(ref);
        if (rc != EOK) {
            ext4_block_set(ref->fs->bdev, &ref->block);
            return rc;
        }

        ext4_bg_clear_flag(bg, EXT4_BLOCK_GROUP_INODE_UNINIT);

        if (!ext4_bg_has_flag(bg, EXT4_BLOCK_GROUP_ITABLE_ZEROED)) {
            rc = ext4_fs_init_inode_table(ref);
            if (rc != EOK) {
                ext4_block_set(fs->bdev, &ref->block);
                return rc;
            }

            ext4_bg_set_flag(bg, EXT4_BLOCK_GROUP_ITABLE_ZEROED);
        }

        ref->dirty = true;
    }

    return EOK;
}

int ext4_fs_put_block_group_ref(struct ext4_block_group_ref *ref) {
    /* Check if reference modified */
    if (ref->dirty) {
        /* Compute new checksum of block group */
        uint16_t cs;
        cs = ext4_fs_bg_checksum(&ref->fs->sb, ref->index, ref->block_group);
        ref->block_group->checksum = to_le16(cs);

        /* Mark block dirty for writing changes to physical device */
        ext4_trans_set_block_dirty(ref->block.buf);
    }

    /* Put back block, that contains block group descriptor */
    return ext4_block_set(ref->fs->bdev, &ref->block);
}

#if CONFIG_META_CSUM_ENABLE
static uint32_t ext4_fs_inode_checksum(struct ext4_inode_ref *inode_ref) {
    uint32_t checksum = 0;
    struct ext4_sblock *sb = &inode_ref->fs->sb;
    uint16_t inode_size = ext4_get16(sb, inode_size);

    if (ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM)) {
        uint32_t orig_checksum;

        uint32_t ino_index = to_le32(inode_ref->index);
        uint32_t ino_gen = to_le32(ext4_inode_get_generation(inode_ref->inode));

        /* Preparation: temporarily set bg checksum to 0 */
        orig_checksum = ext4_inode_get_csum(sb, inode_ref->inode);
        ext4_inode_set_csum(sb, inode_ref->inode, 0);

        /* First calculate crc32 checksum against fs uuid */
        checksum = ext4_crc32c(EXT4_CRC32_INIT, sb->uuid, sizeof(sb->uuid));
        /* Then calculate crc32 checksum against inode number
         * and inode generation */
        checksum = ext4_crc32c(checksum, &ino_index, sizeof(ino_index));
        checksum = ext4_crc32c(checksum, &ino_gen, sizeof(ino_gen));
        /* Finally calculate crc32 checksum against
         * the entire inode */
        checksum = ext4_crc32c(checksum, inode_ref->inode, inode_size);
        ext4_inode_set_csum(sb, inode_ref->inode, orig_checksum);

        /* If inode size is not large enough to hold the
         * upper 16bit of the checksum */
        if (inode_size == EXT4_GOOD_OLD_INODE_SIZE)
            checksum &= 0xFFFF;
    }
    return checksum;
}
#else
#define ext4_fs_inode_checksum(...) 0
#endif

static void ext4_fs_set_inode_checksum(struct ext4_inode_ref *inode_ref) {
    struct ext4_sblock *sb = &inode_ref->fs->sb;
    if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
        return;

    uint32_t csum = ext4_fs_inode_checksum(inode_ref);
    ext4_inode_set_csum(sb, inode_ref->inode, csum);
}

#if CONFIG_META_CSUM_ENABLE
static bool ext4_fs_verify_inode_csum(struct ext4_inode_ref *inode_ref) {
    struct ext4_sblock *sb = &inode_ref->fs->sb;
    if (!ext4_sb_feature_ro_com(sb, EXT4_FRO_COM_METADATA_CSUM))
        return true;

    return ext4_inode_get_csum(sb, inode_ref->inode) ==
           ext4_fs_inode_checksum(inode_ref);
}
#else
#define ext4_fs_verify_inode_csum(...) true
#endif

static int __ext4_fs_get_inode_ref(struct ext4_fs *fs, uint32_t index,
                                   struct ext4_inode_ref *ref,
                                   bool initialized) {
    /* Compute number of i-nodes, that fits in one data block */
    uint32_t inodes_per_group = ext4_get32(&fs->sb, inodes_per_group);

    /*
     * Inode numbers are 1-based, but it is simpler to work with 0-based
     * when computing indices
     */
    index -= 1;
    uint32_t block_group = index / inodes_per_group;
    uint32_t offset_in_group = index % inodes_per_group;

    /* Load block group, where i-node is located */
    struct ext4_block_group_ref bg_ref;

    int rc = ext4_fs_get_block_group_ref(fs, block_group, &bg_ref);
    if (rc != EOK) {
        return rc;
    }

    /* Load block address, where i-node table is located */
    ext4_fsblk_t inode_table_start =
        ext4_bg_get_inode_table_first_block(bg_ref.block_group, &fs->sb);

    /* Put back block group reference (not needed more) */
    rc = ext4_fs_put_block_group_ref(&bg_ref);
    if (rc != EOK) {
        return rc;
    }

    /* Compute position of i-node in the block group */
    uint16_t inode_size = ext4_get16(&fs->sb, inode_size);
    uint32_t block_size = ext4_sb_get_block_size(&fs->sb);
    uint32_t byte_offset_in_group = offset_in_group * inode_size;

    /* Compute block address */
    ext4_fsblk_t block_id =
        inode_table_start + (byte_offset_in_group / block_size);

    rc = ext4_trans_block_get(fs->bdev, &ref->block, block_id);
    if (rc != EOK) {
        return rc;
    }

    /* Compute position of i-node in the data block */
    uint32_t offset_in_block = byte_offset_in_group % block_size;
    ref->inode = (struct ext4_inode *)(ref->block.data + offset_in_block);

    /* We need to store the original value of index in the reference */
    ref->index = index + 1;
    ref->fs = fs;
    ref->dirty = false;

    if (initialized && !ext4_fs_verify_inode_csum(ref)) {
        ext4_dbg(DEBUG_FS,
                 DBG_WARN "Inode checksum failed."
                          "Inode: %" PRIu32 "\n",
                 ref->index);
    }

    return EOK;
}

int ext4_fs_get_inode_ref(struct ext4_fs *fs, uint32_t index,
                          struct ext4_inode_ref *ref) {
    return __ext4_fs_get_inode_ref(fs, index, ref, true);
}

int ext4_fs_put_inode_ref(struct ext4_inode_ref *ref) {
    /* Check if reference modified */
    if (ref->dirty) {
        /* Mark block dirty for writing changes to physical device */
        ext4_fs_set_inode_checksum(ref);
        ext4_trans_set_block_dirty(ref->block.buf);
    }

    /* Put back block, that contains i-node */
    return ext4_block_set(ref->fs->bdev, &ref->block);
}

void ext4_fs_inode_blocks_init(struct ext4_fs *fs,
                               struct ext4_inode_ref *inode_ref) {
    struct ext4_inode *inode = inode_ref->inode;

    /* Reset blocks array. For inode which is not directory or file, just
     * fill in blocks with 0 */
    switch (ext4_inode_type(&fs->sb, inode_ref->inode)) {
    case EXT4_INODE_MODE_FILE:
    case EXT4_INODE_MODE_DIRECTORY:
        break;
    default:
        return;
    }

#if CONFIG_EXTENT_ENABLE && CONFIG_EXTENTS_ENABLE
    /* Initialize extents if needed */
    if (ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS)) {
        ext4_inode_set_flag(inode, EXT4_INODE_FLAG_EXTENTS);

        /* Initialize extent root header */
        ext4_extent_tree_init(inode_ref);
    }

    inode_ref->dirty = true;
#endif
}

uint32_t ext4_fs_correspond_inode_mode(int filetype) {
    switch (filetype) {
    case EXT4_DE_DIR:
        return EXT4_INODE_MODE_DIRECTORY;
    case EXT4_DE_REG_FILE:
        return EXT4_INODE_MODE_FILE;
    case EXT4_DE_SYMLINK:
        return EXT4_INODE_MODE_SOFTLINK;
    case EXT4_DE_CHRDEV:
        return EXT4_INODE_MODE_CHARDEV;
    case EXT4_DE_BLKDEV:
        return EXT4_INODE_MODE_BLOCKDEV;
    case EXT4_DE_FIFO:
        return EXT4_INODE_MODE_FIFO;
    case EXT4_DE_SOCK:
        return EXT4_INODE_MODE_SOCKET;
    }
    /* FIXME: unsupported filetype */
    return EXT4_INODE_MODE_FILE;
}

int ext4_fs_alloc_inode(struct ext4_fs *fs, struct ext4_inode_ref *inode_ref,
                        int filetype) {
    /* Check if newly allocated i-node will be a directory */
    bool is_dir;
    uint16_t inode_size = ext4_get16(&fs->sb, inode_size);

    is_dir = (filetype == EXT4_DE_DIR);

    /* Allocate inode by allocation algorithm */
    uint32_t index;
    int rc = ext4_ialloc_alloc_inode(fs, &index, is_dir);
    if (rc != EOK)
        return rc;

    /* Load i-node from on-disk i-node table */
    rc = __ext4_fs_get_inode_ref(fs, index, inode_ref, false);
    if (rc != EOK) {
        ext4_ialloc_free_inode(fs, index, is_dir);
        return rc;
    }

    /* Initialize i-node */
    struct ext4_inode *inode = inode_ref->inode;

    memset(inode, 0, inode_size);

    uint32_t mode;
    if (is_dir) {
        /*
         * Default directory permissions to be compatible with other
         * systems
         * 0777 (octal) == rwxrwxrwx
         */

        mode = 0777;
        mode |= EXT4_INODE_MODE_DIRECTORY;
    } else if (filetype == EXT4_DE_SYMLINK) {
        /*
         * Default symbolic link permissions to be compatible with other systems
         * 0777 (octal) == rwxrwxrwx
         */

        mode = 0777;
        mode |= EXT4_INODE_MODE_SOFTLINK;
    } else {
        /*
         * Default file permissions to be compatible with other systems
         * 0666 (octal) == rw-rw-rw-
         */

        mode = 0666;
        mode |= ext4_fs_correspond_inode_mode(filetype);
    }
    ext4_inode_set_mode(&fs->sb, inode, mode);

    ext4_inode_set_links_cnt(inode, 0);
    ext4_inode_set_uid(inode, 0);
    ext4_inode_set_gid(inode, 0);
    ext4_inode_set_size(inode, 0);
    ext4_inode_set_access_time(inode, 0);
    ext4_inode_set_change_inode_time(inode, 0);
    ext4_inode_set_modif_time(inode, 0);
    ext4_inode_set_del_time(inode, 0);
    ext4_inode_set_blocks_count(&fs->sb, inode, 0);
    ext4_inode_set_flags(inode, 0);
    ext4_inode_set_generation(inode, 0);
    if (inode_size > EXT4_GOOD_OLD_INODE_SIZE) {
        uint16_t size = ext4_get16(&fs->sb, want_extra_isize);
        ext4_inode_set_extra_isize(&fs->sb, inode, size);
    }

    memset(inode->blocks, 0, sizeof(inode->blocks));
    inode_ref->dirty = true;

    return EOK;
}

int ext4_fs_free_inode(struct ext4_inode_ref *inode_ref) {
    struct ext4_fs *fs = inode_ref->fs;
    uint32_t offset;
    uint32_t suboff;
    int rc;
#if CONFIG_EXTENT_ENABLE && CONFIG_EXTENTS_ENABLE
    /* For extents must be data block destroyed by other way */
    if ((ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS)) &&
        (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {
        /* Data structures are released during truncate operation... */
        goto finish;
    }
#endif
    /* Release all indirect (no data) blocks */

    /* 1) Single indirect */
    ext4_fsblk_t fblock = ext4_inode_get_indirect_block(inode_ref->inode, 0);
    if (fblock != 0) {
        int rc = ext4_balloc_free_block(inode_ref, fblock);
        if (rc != EOK)
            return rc;

        ext4_inode_set_indirect_block(inode_ref->inode, 0, 0);
    }

    uint32_t block_size = ext4_sb_get_block_size(&fs->sb);
    uint32_t count = block_size / sizeof(uint32_t);

    struct ext4_block block;

    /* 2) Double indirect */
    fblock = ext4_inode_get_indirect_block(inode_ref->inode, 1);
    if (fblock != 0) {
        int rc = ext4_trans_block_get(fs->bdev, &block, fblock);
        if (rc != EOK)
            return rc;

        ext4_fsblk_t ind_block;
        for (offset = 0; offset < count; ++offset) {
            ind_block = to_le32(((uint32_t *)block.data)[offset]);

            if (ind_block == 0)
                continue;
            rc = ext4_balloc_free_block(inode_ref, ind_block);
            if (rc != EOK) {
                ext4_block_set(fs->bdev, &block);
                return rc;
            }
        }

        ext4_block_set(fs->bdev, &block);
        rc = ext4_balloc_free_block(inode_ref, fblock);
        if (rc != EOK)
            return rc;

        ext4_inode_set_indirect_block(inode_ref->inode, 1, 0);
    }

    /* 3) Tripple indirect */
    struct ext4_block subblock;
    fblock = ext4_inode_get_indirect_block(inode_ref->inode, 2);
    if (fblock == 0)
        goto finish;
    rc = ext4_trans_block_get(fs->bdev, &block, fblock);
    if (rc != EOK)
        return rc;

    ext4_fsblk_t ind_block;
    for (offset = 0; offset < count; ++offset) {
        ind_block = to_le32(((uint32_t *)block.data)[offset]);

        if (ind_block == 0)
            continue;
        rc = ext4_trans_block_get(fs->bdev, &subblock, ind_block);
        if (rc != EOK) {
            ext4_block_set(fs->bdev, &block);
            return rc;
        }

        ext4_fsblk_t ind_subblk;
        for (suboff = 0; suboff < count; ++suboff) {
            ind_subblk = to_le32(((uint32_t *)subblock.data)[suboff]);

            if (ind_subblk == 0)
                continue;
            rc = ext4_balloc_free_block(inode_ref, ind_subblk);
            if (rc != EOK) {
                ext4_block_set(fs->bdev, &subblock);
                ext4_block_set(fs->bdev, &block);
                return rc;
            }
        }

        ext4_block_set(fs->bdev, &subblock);

        rc = ext4_balloc_free_block(inode_ref, ind_block);
        if (rc != EOK) {
            ext4_block_set(fs->bdev, &block);
            return rc;
        }
    }

    ext4_block_set(fs->bdev, &block);
    rc = ext4_balloc_free_block(inode_ref, fblock);
    if (rc != EOK)
        return rc;

    ext4_inode_set_indirect_block(inode_ref->inode, 2, 0);
finish:
    /* Mark inode dirty for writing to the physical device */
    inode_ref->dirty = true;

    /* Free block with extended attributes if present */
    ext4_fsblk_t xattr_block =
        ext4_inode_get_file_acl(inode_ref->inode, &fs->sb);
    if (xattr_block) {
        int rc = ext4_balloc_free_block(inode_ref, xattr_block);
        if (rc != EOK)
            return rc;

        ext4_inode_set_file_acl(inode_ref->inode, &fs->sb, 0);
    }

    /* Free inode by allocator */
    if (ext4_inode_is_type(&fs->sb, inode_ref->inode,
                           EXT4_INODE_MODE_DIRECTORY))
        rc = ext4_ialloc_free_inode(fs, inode_ref->index, true);
    else
        rc = ext4_ialloc_free_inode(fs, inode_ref->index, false);

    return rc;
}

/**@brief Release data block from i-node
 * @param inode_ref I-node to release block from
 * @param iblock    Logical block to be released
 * @return Error code
 */
static int ext4_fs_release_inode_block(struct ext4_inode_ref *inode_ref,
                                       ext4_lblk_t iblock) {
    ext4_fsblk_t fblock;

    struct ext4_fs *fs = inode_ref->fs;

    /* Extents are handled otherwise = there is not support in this function
     */
    ext4_assert(
        !(ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS) &&
          (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))));

    struct ext4_inode *inode = inode_ref->inode;

    /* Handle simple case when we are dealing with direct reference */
    if (iblock < EXT4_INODE_DIRECT_BLOCK_COUNT) {
        fblock = ext4_inode_get_direct_block(inode, iblock);

        /* Sparse file */
        if (fblock == 0)
            return EOK;

        ext4_inode_set_direct_block(inode, iblock, 0);
        return ext4_balloc_free_block(inode_ref, fblock);
    }

    /* Determine the indirection level needed to get the desired block */
    unsigned int level = 0;
    unsigned int i;
    for (i = 1; i < 4; i++) {
        if (iblock < fs->inode_block_limits[i]) {
            level = i;
            break;
        }
    }

    if (level == 0)
        return EIO;

    /* Compute offsets for the topmost level */
    uint32_t block_offset_in_level =
        (uint32_t)(iblock - fs->inode_block_limits[level - 1]);
    ext4_fsblk_t current_block =
        ext4_inode_get_indirect_block(inode, level - 1);
    uint32_t offset_in_block =
        (uint32_t)(block_offset_in_level /
                   fs->inode_blocks_per_level[level - 1]);

    /*
     * Navigate through other levels, until we find the block number
     * or find null reference meaning we are dealing with sparse file
     */
    struct ext4_block block;

    while (level > 0) {

        /* Sparse check */
        if (current_block == 0)
            return EOK;

        int rc = ext4_trans_block_get(fs->bdev, &block, current_block);
        if (rc != EOK)
            return rc;

        current_block = to_le32(((uint32_t *)block.data)[offset_in_block]);

        /* Set zero if physical data block address found */
        if (level == 1) {
            ((uint32_t *)block.data)[offset_in_block] = to_le32(0);
            ext4_trans_set_block_dirty(block.buf);
        }

        rc = ext4_block_set(fs->bdev, &block);
        if (rc != EOK)
            return rc;

        level--;

        /*
         * If we are on the last level, break here as
         * there is no next level to visit
         */
        if (level == 0)
            break;

        /* Visit the next level */
        block_offset_in_level %= fs->inode_blocks_per_level[level];
        offset_in_block = (uint32_t)(block_offset_in_level /
                                     fs->inode_blocks_per_level[level - 1]);
    }

    fblock = current_block;
    if (fblock == 0)
        return EOK;

    /* Physical block is not referenced, it can be released */
    return ext4_balloc_free_block(inode_ref, fblock);
}

int ext4_fs_truncate_inode(struct ext4_inode_ref *inode_ref,
                           uint64_t new_size) {
    struct ext4_sblock *sb = &inode_ref->fs->sb;
    uint32_t i;
    int r;
    bool v;

    /* Check flags, if i-node can be truncated */
    if (!ext4_inode_can_truncate(sb, inode_ref->inode))
        return EINVAL;

    /* If sizes are equal, nothing has to be done. */
    uint64_t old_size = ext4_inode_get_size(sb, inode_ref->inode);
    if (old_size == new_size)
        return EOK;

    /* It's not supported to make the larger file by truncate operation */
    if (old_size < new_size)
        return EINVAL;

    /* For symbolic link which is small enough */
    v = ext4_inode_is_type(sb, inode_ref->inode, EXT4_INODE_MODE_SOFTLINK);
    if (v && old_size < sizeof(inode_ref->inode->blocks) &&
        !ext4_inode_get_blocks_count(sb, inode_ref->inode)) {
        char *content = (char *)inode_ref->inode->blocks + new_size;
        memset(content, 0,
               sizeof(inode_ref->inode->blocks) - (uint32_t)new_size);
        ext4_inode_set_size(inode_ref->inode, new_size);
        inode_ref->dirty = true;

        return EOK;
    }

    i = ext4_inode_type(sb, inode_ref->inode);
    if (i == EXT4_INODE_MODE_CHARDEV || i == EXT4_INODE_MODE_BLOCKDEV ||
        i == EXT4_INODE_MODE_SOCKET) {
        inode_ref->inode->blocks[0] = 0;
        inode_ref->inode->blocks[1] = 0;

        inode_ref->dirty = true;
        return EOK;
    }

    /* Compute how many blocks will be released */
    uint32_t block_size = ext4_sb_get_block_size(sb);
    uint32_t new_blocks_cnt =
        (uint32_t)((new_size + block_size - 1) / block_size);
    uint32_t old_blocks_cnt =
        (uint32_t)((old_size + block_size - 1) / block_size);
    uint32_t diff_blocks_cnt = old_blocks_cnt - new_blocks_cnt;
#if CONFIG_EXTENT_ENABLE && CONFIG_EXTENTS_ENABLE
    if ((ext4_sb_feature_incom(sb, EXT4_FINCOM_EXTENTS)) &&
        (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {

        /* Extents require special operation */
        if (diff_blocks_cnt) {
            r = ext4_extent_remove_space(inode_ref, new_blocks_cnt,
                                         EXT_MAX_BLOCKS);
            if (r != EOK)
                return r;
        }
    } else
#endif
    {
        /* Release data blocks from the end of file */

        /* Starting from 1 because of logical blocks are numbered from 0
         */
        for (i = 0; i < diff_blocks_cnt; ++i) {
            r = ext4_fs_release_inode_block(inode_ref, new_blocks_cnt + i);
            if (r != EOK)
                return r;
        }
    }

    /* Update i-node */
    ext4_inode_set_size(inode_ref->inode, new_size);
    inode_ref->dirty = true;

    return EOK;
}

/**@brief Compute 'goal' for inode index
 * @param inode_ref Reference to inode, to allocate block for
 * @return goal
 */
ext4_fsblk_t ext4_fs_inode_to_goal_block(struct ext4_inode_ref *inode_ref) {
    uint32_t grp_inodes = ext4_get32(&inode_ref->fs->sb, inodes_per_group);
    return (inode_ref->index - 1) / grp_inodes;
}

/**@brief Compute 'goal' for allocation algorithm (For blockmap).
 * @param inode_ref Reference to inode, to allocate block for
 * @return error code
 */
int ext4_fs_indirect_find_goal(struct ext4_inode_ref *inode_ref,
                               ext4_fsblk_t *goal) {
    int r;
    struct ext4_sblock *sb = &inode_ref->fs->sb;
    *goal = 0;

    uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
    uint32_t block_size = ext4_sb_get_block_size(sb);
    uint32_t iblock_cnt = (uint32_t)(inode_size / block_size);

    if (inode_size % block_size != 0)
        iblock_cnt++;

    /* If inode has some blocks, get last block address + 1 */
    if (iblock_cnt > 0) {
        r = ext4_fs_get_inode_dblk_idx(inode_ref, iblock_cnt - 1, goal, false);
        if (r != EOK)
            return r;

        if (*goal != 0) {
            (*goal)++;
            return r;
        }

        /* If goal == 0, sparse file -> continue */
    }

    /* Identify block group of inode */

    uint32_t inodes_per_bg = ext4_get32(sb, inodes_per_group);
    uint32_t block_group = (inode_ref->index - 1) / inodes_per_bg;
    block_size = ext4_sb_get_block_size(sb);

    /* Load block group reference */
    struct ext4_block_group_ref bg_ref;
    r = ext4_fs_get_block_group_ref(inode_ref->fs, block_group, &bg_ref);
    if (r != EOK)
        return r;

    struct ext4_bgroup *bg = bg_ref.block_group;

    /* Compute indexes */
    uint32_t bg_count = ext4_block_group_cnt(sb);
    ext4_fsblk_t itab_first_block = ext4_bg_get_inode_table_first_block(bg, sb);
    uint16_t itab_item_size = ext4_get16(sb, inode_size);
    uint32_t itab_bytes;

    /* Check for last block group */
    if (block_group < bg_count - 1) {
        itab_bytes = inodes_per_bg * itab_item_size;
    } else {
        /* Last block group could be smaller */
        uint32_t inodes_cnt = ext4_get32(sb, inodes_count);

        itab_bytes = (inodes_cnt - ((bg_count - 1) * inodes_per_bg));
        itab_bytes *= itab_item_size;
    }

    ext4_fsblk_t inode_table_blocks = itab_bytes / block_size;

    if (itab_bytes % block_size)
        inode_table_blocks++;

    *goal = itab_first_block + inode_table_blocks;

    return ext4_fs_put_block_group_ref(&bg_ref);
}

static int ext4_fs_get_inode_dblk_idx_internal(
    struct ext4_inode_ref *inode_ref, ext4_lblk_t iblock, ext4_fsblk_t *fblock,
    bool extent_create, bool support_unwritten __unused) {
    struct ext4_fs *fs = inode_ref->fs;

    /* For empty file is situation simple */
    if (ext4_inode_get_size(&fs->sb, inode_ref->inode) == 0) {
        *fblock = 0;
        return EOK;
    }

    ext4_fsblk_t current_block;

    (void)extent_create;
#if CONFIG_EXTENT_ENABLE && CONFIG_EXTENTS_ENABLE
    /* Handle i-node using extents */
    if ((ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS)) &&
        (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {

        ext4_fsblk_t current_fsblk;
        int rc = ext4_extent_get_blocks(inode_ref, iblock, 1, &current_fsblk,
                                        extent_create, NULL);
        if (rc != EOK)
            return rc;

        current_block = current_fsblk;
        *fblock = current_block;

        ext4_assert(*fblock || support_unwritten);
        return EOK;
    }
#endif

    struct ext4_inode *inode = inode_ref->inode;

    /* Direct block are read directly from array in i-node structure */
    if (iblock < EXT4_INODE_DIRECT_BLOCK_COUNT) {
        current_block = ext4_inode_get_direct_block(inode, (uint32_t)iblock);
        *fblock = current_block;
        return EOK;
    }

    /* Determine indirection level of the target block */
    unsigned int l = 0;
    unsigned int i;
    for (i = 1; i < 4; i++) {
        if (iblock < fs->inode_block_limits[i]) {
            l = i;
            break;
        }
    }

    if (l == 0)
        return EIO;

    /* Compute offsets for the topmost level */
    uint32_t blk_off_in_lvl =
        (uint32_t)(iblock - fs->inode_block_limits[l - 1]);
    current_block = ext4_inode_get_indirect_block(inode, l - 1);
    uint32_t off_in_blk =
        (uint32_t)(blk_off_in_lvl / fs->inode_blocks_per_level[l - 1]);

    /* Sparse file */
    if (current_block == 0) {
        *fblock = 0;
        return EOK;
    }

    struct ext4_block block;

    /*
     * Navigate through other levels, until we find the block number
     * or find null reference meaning we are dealing with sparse file
     */
    while (l > 0) {
        /* Load indirect block */
        int rc = ext4_trans_block_get(fs->bdev, &block, current_block);
        if (rc != EOK)
            return rc;

        /* Read block address from indirect block */
        current_block = to_le32(((uint32_t *)block.data)[off_in_blk]);

        /* Put back indirect block untouched */
        rc = ext4_block_set(fs->bdev, &block);
        if (rc != EOK)
            return rc;

        /* Check for sparse file */
        if (current_block == 0) {
            *fblock = 0;
            return EOK;
        }

        /* Jump to the next level */
        l--;

        /* Termination condition - we have address of data block loaded
         */
        if (l == 0)
            break;

        /* Visit the next level */
        blk_off_in_lvl %= fs->inode_blocks_per_level[l];
        off_in_blk =
            (uint32_t)(blk_off_in_lvl / fs->inode_blocks_per_level[l - 1]);
    }

    *fblock = current_block;

    return EOK;
}

int ext4_fs_get_inode_dblk_idx(struct ext4_inode_ref *inode_ref,
                               ext4_lblk_t iblock, ext4_fsblk_t *fblock,
                               bool support_unwritten) {
    return ext4_fs_get_inode_dblk_idx_internal(inode_ref, iblock, fblock, false,
                                               support_unwritten);
}

int ext4_fs_init_inode_dblk_idx(struct ext4_inode_ref *inode_ref,
                                ext4_lblk_t iblock, ext4_fsblk_t *fblock) {
    return ext4_fs_get_inode_dblk_idx_internal(inode_ref, iblock, fblock, true,
                                               true);
}

static int ext4_fs_set_inode_data_block_index(struct ext4_inode_ref *inode_ref,
                                              ext4_lblk_t iblock,
                                              ext4_fsblk_t fblock) {
    struct ext4_fs *fs = inode_ref->fs;

#if CONFIG_EXTENT_ENABLE && CONFIG_EXTENTS_ENABLE
    /* Handle inode using extents */
    if ((ext4_sb_feature_incom(&fs->sb, EXT4_FINCOM_EXTENTS)) &&
        (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {
        /* Not reachable */
        return ENOTSUP;
    }
#endif

    /* Handle simple case when we are dealing with direct reference */
    if (iblock < EXT4_INODE_DIRECT_BLOCK_COUNT) {
        ext4_inode_set_direct_block(inode_ref->inode, (uint32_t)iblock,
                                    (uint32_t)fblock);
        inode_ref->dirty = true;

        return EOK;
    }

    /* Determine the indirection level needed to get the desired block */
    unsigned int l = 0;
    unsigned int i;
    for (i = 1; i < 4; i++) {
        if (iblock < fs->inode_block_limits[i]) {
            l = i;
            break;
        }
    }

    if (l == 0)
        return EIO;

    uint32_t block_size = ext4_sb_get_block_size(&fs->sb);

    /* Compute offsets for the topmost level */
    uint32_t blk_off_in_lvl =
        (uint32_t)(iblock - fs->inode_block_limits[l - 1]);
    ext4_fsblk_t current_block =
        ext4_inode_get_indirect_block(inode_ref->inode, l - 1);
    uint32_t off_in_blk =
        (uint32_t)(blk_off_in_lvl / fs->inode_blocks_per_level[l - 1]);

    ext4_fsblk_t new_blk;

    struct ext4_block block;
    struct ext4_block new_block;

    /* Is needed to allocate indirect block on the i-node level */
    if (current_block == 0) {
        /* Allocate new indirect block */
        ext4_fsblk_t goal;
        int rc = ext4_fs_indirect_find_goal(inode_ref, &goal);
        if (rc != EOK)
            return rc;

        rc = ext4_balloc_alloc_block(inode_ref, goal, &new_blk);
        if (rc != EOK)
            return rc;

        /* Update i-node */
        ext4_inode_set_indirect_block(inode_ref->inode, l - 1,
                                      (uint32_t)new_blk);
        inode_ref->dirty = true;

        /* Load newly allocated block */
        rc = ext4_trans_block_get_noread(fs->bdev, &new_block, new_blk);
        if (rc != EOK) {
            ext4_balloc_free_block(inode_ref, new_blk);
            return rc;
        }

        /* Initialize new block */
        memset(new_block.data, 0, block_size);
        ext4_trans_set_block_dirty(new_block.buf);

        /* Put back the allocated block */
        rc = ext4_block_set(fs->bdev, &new_block);
        if (rc != EOK)
            return rc;

        current_block = new_blk;
    }

    /*
     * Navigate through other levels, until we find the block number
     * or find null reference meaning we are dealing with sparse file
     */
    while (l > 0) {
        int rc = ext4_trans_block_get(fs->bdev, &block, current_block);
        if (rc != EOK)
            return rc;

        current_block = to_le32(((uint32_t *)block.data)[off_in_blk]);
        if ((l > 1) && (current_block == 0)) {
            ext4_fsblk_t goal;
            rc = ext4_fs_indirect_find_goal(inode_ref, &goal);
            if (rc != EOK) {
                ext4_block_set(fs->bdev, &block);
                return rc;
            }

            /* Allocate new block */
            rc = ext4_balloc_alloc_block(inode_ref, goal, &new_blk);
            if (rc != EOK) {
                ext4_block_set(fs->bdev, &block);
                return rc;
            }

            /* Load newly allocated block */
            rc = ext4_trans_block_get_noread(fs->bdev, &new_block, new_blk);

            if (rc != EOK) {
                ext4_block_set(fs->bdev, &block);
                return rc;
            }

            /* Initialize allocated block */
            memset(new_block.data, 0, block_size);
            ext4_trans_set_block_dirty(new_block.buf);

            rc = ext4_block_set(fs->bdev, &new_block);
            if (rc != EOK) {
                ext4_block_set(fs->bdev, &block);
                return rc;
            }

            /* Write block address to the parent */
            uint32_t *p = (uint32_t *)block.data;
            p[off_in_blk] = to_le32((uint32_t)new_blk);
            ext4_trans_set_block_dirty(block.buf);
            current_block = new_blk;
        }

        /* Will be finished, write the fblock address */
        if (l == 1) {
            uint32_t *p = (uint32_t *)block.data;
            p[off_in_blk] = to_le32((uint32_t)fblock);
            ext4_trans_set_block_dirty(block.buf);
        }

        rc = ext4_block_set(fs->bdev, &block);
        if (rc != EOK)
            return rc;

        l--;

        /*
         * If we are on the last level, break here as
         * there is no next level to visit
         */
        if (l == 0)
            break;

        /* Visit the next level */
        blk_off_in_lvl %= fs->inode_blocks_per_level[l];
        off_in_blk =
            (uint32_t)(blk_off_in_lvl / fs->inode_blocks_per_level[l - 1]);
    }

    return EOK;
}

int ext4_fs_append_inode_dblk(struct ext4_inode_ref *inode_ref,
                              ext4_fsblk_t *fblock, ext4_lblk_t *iblock) {
#if CONFIG_EXTENT_ENABLE && CONFIG_EXTENTS_ENABLE
    /* Handle extents separately */
    if ((ext4_sb_feature_incom(&inode_ref->fs->sb, EXT4_FINCOM_EXTENTS)) &&
        (ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_EXTENTS))) {
        int rc;
        ext4_fsblk_t current_fsblk;
        struct ext4_sblock *sb = &inode_ref->fs->sb;
        uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
        uint32_t block_size = ext4_sb_get_block_size(sb);
        *iblock = (uint32_t)((inode_size + block_size - 1) / block_size);

        rc = ext4_extent_get_blocks(inode_ref, *iblock, 1, &current_fsblk, true,
                                    NULL);
        if (rc != EOK)
            return rc;

        *fblock = current_fsblk;
        ext4_assert(*fblock);

        ext4_inode_set_size(inode_ref->inode, inode_size + block_size);
        inode_ref->dirty = true;

        return rc;
    }
#endif
    struct ext4_sblock *sb = &inode_ref->fs->sb;

    /* Compute next block index and allocate data block */
    uint64_t inode_size = ext4_inode_get_size(sb, inode_ref->inode);
    uint32_t block_size = ext4_sb_get_block_size(sb);

    /* Align size i-node size */
    if ((inode_size % block_size) != 0)
        inode_size += block_size - (inode_size % block_size);

    /* Logical blocks are numbered from 0 */
    uint32_t new_block_idx = (uint32_t)(inode_size / block_size);

    /* Allocate new physical block */
    ext4_fsblk_t goal, phys_block;
    int rc = ext4_fs_indirect_find_goal(inode_ref, &goal);
    if (rc != EOK)
        return rc;

    rc = ext4_balloc_alloc_block(inode_ref, goal, &phys_block);
    if (rc != EOK)
        return rc;

    /* Add physical block address to the i-node */
    rc = ext4_fs_set_inode_data_block_index(inode_ref, new_block_idx,
                                            phys_block);
    if (rc != EOK) {
        ext4_balloc_free_block(inode_ref, phys_block);
        return rc;
    }

    /* Update i-node */
    ext4_inode_set_size(inode_ref->inode, inode_size + block_size);
    inode_ref->dirty = true;

    *fblock = phys_block;
    *iblock = new_block_idx;

    return EOK;
}

void ext4_fs_inode_links_count_inc(struct ext4_inode_ref *inode_ref) {
    uint16_t link;
    bool is_dx;
    link = ext4_inode_get_links_cnt(inode_ref->inode);
    link++;
    ext4_inode_set_links_cnt(inode_ref->inode, link);

    is_dx = ext4_sb_feature_com(&inode_ref->fs->sb, EXT4_FCOM_DIR_INDEX) &&
            ext4_inode_has_flag(inode_ref->inode, EXT4_INODE_FLAG_INDEX);

    if (is_dx && link > 1) {
        if (link >= EXT4_LINK_MAX || link == 2) {
            ext4_inode_set_links_cnt(inode_ref->inode, 1);

            uint32_t v;
            v = ext4_get32(&inode_ref->fs->sb, features_read_only);
            v |= EXT4_FRO_COM_DIR_NLINK;
            ext4_set32(&inode_ref->fs->sb, features_read_only, v);
        }
    }
}

void ext4_fs_inode_links_count_dec(struct ext4_inode_ref *inode_ref) {
    uint16_t links = ext4_inode_get_links_cnt(inode_ref->inode);
    if (!ext4_inode_is_type(&inode_ref->fs->sb, inode_ref->inode,
                            EXT4_INODE_MODE_DIRECTORY)) {
        if (links > 0)
            ext4_inode_set_links_cnt(inode_ref->inode, links - 1);
        return;
    }

    if (links > 2)
        ext4_inode_set_links_cnt(inode_ref->inode, links - 1);
}

/**
 * @}
 */
